Method of treating metallic particles



Patented Dec. 4, 1928.

UNITED-STATES eeann career caries.

GEORGE E. DALBEY, OF EAST BERLIN, AND THOMAS P. HANFORD, OF BERLIN, CON-NECTICUT, ASSIGNORS TO THE STANLEY CHEMICAL COMPANY, OF EAST BERLIN,CONNECTICUT, A CORPORATION OF CONNECTICUT.

METHOD OF TREATING METALLIC PARTICLES.

No Drawing.

This invention relates to a method of treating metallic particles.

More particularly the invention relates to the treatment of metallicparticles of lead alloys containing arsenic, tin and antimony, or one ormore of such metals. It is to be understood that the term alloy isintended to include impure lead in which the arsenic, tin or antimonyappear as impurities.

l0 The metallic'particles to be treated may be derived from varioussources and in various ways. For example, certain metallic dresses,which are subject to reclamation treatment, consist largely of alloys ofarsenic, tin, an-

timony and lead. By known methods of concentration it is possible toseparate the metallic particles. from these drosses. Such a source ofmetallic particles is referred to in a copending application filed ofeven date herewith, Serial No. 161,236.

i It is an object'of the present invention to provide a commerciallyeconomical method of treating the metallic particles referred to, toseparate them into their component metals or into chemical compounds ofsuch metals, thereby obtaining products of commercial value;

With this general object in view, the invention consists in the methodwhich is here- 0 inafter described and then more particularly pointedout in the claims.

In carrying out the method of the invention, the metallic particles aresubjected to the influence of an alkali metal hydroxide in 5 thepresence of an oxidizing agent. In carrying out the invention to what isnow considered the best advantage the metallic particles arecontinuously agitated in a water solution of caustic soda to which hasbeen 40 added an oxidizing agent. This may be done in a rolling barrelor by other suitable means.

While various oxidizing agents may be used sodium nitrate or oxide oflead, e. g. litharge, have been found suitable.

In the use of sodium nitrate the metallics are oxidized and theresulting oxides combine with the caustic soda to form sodiummetalsalts, e. g. sodium arsenate, sodium stannate, sodium antimonate andsodium plumbate.

In the use of an oxide of lead, such as litharge, the metals other thanlead, e. g. arsenic, tin and antimony, are oxidized with Applicationfiled January 14, 1927. Serial No. 161,235.

the consequent reduction of the lead oxide to metallic lead. It isprobable that a certain amount of the lead oxide is reacted upon by thecaustic soda to form some sodium plumbate or plumbite. The latter,however, itself reacts with the metallic arsenic, tin and antimony tocause reduction of the sodium plumbate or plumbite to metallic lead. Andthere is formed sodium salts of the other metals, e. g. sodium arsenate,sodium stannate and sodium antimonate.

Vhile the conditions under which these reactions are carried out mayvary as to temperatures and pressures, room temperatures and atmosphericpressure have been found suitable. Such conditions, moreover, make forsimplicity of apparatus and operation.

lVhatever the means of oxidation the results are the same except thatmetallic lead is precipitated when lead oxide is used.

As a result of the steps described the metallic particles are separatedinto their component metals or chemical compounds of these metals. Theresulting solution or suspension of the sodium compounds, which mayinclude free uncombined caustic soda, is capable of further treatmentfor the recovery of valuable products, for example, by the processdisclosedin a copending application filed of even date herewith, SerialNo. 161,238. Likewise the resulting sludge which may contain metalliclead can be further treated for the recovery of values.

What is claimed is:

1. The method of treating metallic particles of lead alloys containingone or more of the metals tin, antimony, arsenic, which comprisessubjecting the particles, at temperatures substantially below the fusingoint thereof, to the influence of a water soution of an alkali metal inthe presence of an oxidizing agent. i

2. The method of treating metallic particles of lead alloys containingone or more of the metals tin, antimony, arsenic, which comprisesoxidizing the particles and causing the resulting oxides to react withcaustic soda to form sodium salts of the metals, all at temperaturessubstantially below the ins ing: point of the metal particles.

3. The method of treating metallic particles of lead alloys containingone or more Mai 2 meson of the metals tin, antimony, arsenic, which allat temperatures substantially below the comprises subjecting theparticles to the infusing point of the metal particles. fluence of aWater solution of caustic soda In testimony whereof, We have hereunto inthe presence of an oxide of lead, whereby set our hands.

5 the oxide of lead is reduced to metallic lead and the oxides of theother metals react with GEORGE E. the caustic soda to form sodium-metalsalts, THOMAS P, HANFORD.

